1. Field of the Invention
The present invention relates to photoresists which are highly sensitive to deep ultraviolet and vacuum ultraviolet radiation and which are developable in a dry process. Such compositions are highly absorbing in the deep ultraviolet spectrum and are functionalized so that their reactivity to organometallic reagents in exposed regions and unexposed regions is greatly differentiated.
2. Background Art
U.S. Pat. No. 4,491,628 discloses resist compositions which comprise certain polymers having acid labile groups pendant thereto and a photoinitiator which generates strong acid upon exposure to radiation. The preferred polymers are vinylics having aromatic rings (i.e. styrenes) although other polymerizations such as condensation, polyaddition and addition condensation are also useful. The photoinitiators used included diaryliodonium, triarylsulfonium, triarylselenonium and aryldiazonium salts. The resulting resists form solvent developable systems which are positive working when developed with an (aqueous) alkaline developer or polar solvent and are negative working when developed with a non-polar solvent. The developed, patterned resists formed provide useful structures due to their resistance to plasma and reactive ion etching (RIE).
U.S. Pat. No. 4,552,833 shows the use of resist compositions having a photo labile or acid labile group masking or protecting a functional group and groups on a resist polymer and a species that is capable of generating acid upon exposure to radiation. Films of that composition may be imaged and reacted with an organometallic agent in the exposed regions and then subjected to an oxygen plasma environment to provide high resolution, negative tone relief images.
F. Houlihan, F. Bouchard, J. M. J. Frechet, and C. G. Willson, Can. J. Chem., 63, 153 (1985), discloses that the tert-butyloxycarbonylation of phenols, alcohols, enols, and thiols can be accomplished by reaction of these functionalities with di-tert-butyl dicarbonate under phase transfer conditions. An example of tert-butyloxycarbonylation of novolak is given.
U.S. Pat. No. 4,810,601 shows the use of resist compositions having at least one component which undergoes molecular rearrangement upon irradiation to produce active hydrogens, irradiating the surface layer of films of such materials to form reaction products in the upper portion of such layer, and treating the reaction products with a reactive organometallic reagent to make the upper portion dry etch resistant.